遇到一个奇怪的 js 问题

[isbase]

注意看变量reg的位置变化




https://gist.github.com/isbaseby/705828a6e9aed2388386d43a1e374e80

```
function filtrate2() {
var newArr = [], reg = /^\s*$/g,
str = "baidu,google, , ,baidu,google,bg";
arr = str.split(',');
for (var i = 0; i < arr.length; i++) {
//var reg = /^\s*$/g;
if (!reg.test(arr[i])) {
newArr.push(arr[i]);
}
}
return newArr;
}

//执行结果 ["baidu", "google", " ", "baidu", "google", "bg"]



function filtrate2() {
var newArr = [], reg = /^\s*$/g,
str = "baidu,google, , ,baidu,google,bg";
arr = str.split(',');
for (var i = 0; i < arr.length; i++) {
var reg = /^\s*$/g;
if (!reg.test(arr[i])) {
newArr.push(arr[i]);
}
}
return newArr;
}

//执行结果 ["baidu", "google", "baidu", "google", "bg"]
```

我觉得是和 js 的作用域有关，但又说不清楚，请各位赐教。

[Niris]

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/lastIndex

[isbase]

@Niris Thanks

[w88975]

function filtrate2() {
var newArr = [], reg = /^\s*$/g,
str = "baidu,google, , ,baidu,google,bg";
arr = str.split(',');
for (var i = 0; i < arr.length; i++) {
if (!reg.test(arr[i])) {
newArr.push(arr[i]);
}
reg.lastIndex = 0;
}
return newArr;
}

[Arrowing]

arr = str.split(','); 导致的，这里的 arr 是全局对象下的 arr
前面一行最后面是分号，不是逗号！！！！

[Arrowing]

啊，看错题了，忽略上一条 0.0

[Arrowing]

1 楼说得对，是因为 lastIndex 被改变了，重新定义的 reg 对象又初始化了 lastIndex

[isbase]

@Arrowing 这个细节没注意到
@w88975

Thanks